Metal-oxide-semiconductor (MOS) transistors are one of the important components in modern integrated circuits (ICs). The basic structure of an MOS transistor includes a semiconductor substrate, a gate structure formed on the semiconductor substrate, and source/drain regions formed in the semiconductor substrate at two sides of the gate structure. The gate structure includes a gate dielectric layer formed on the surface of the semiconductor substrate and a gate electrode layer formed on the gate dielectric layer.
With the continuous development of the semiconductor technology, the control ability of the gate structures of the conventional planar MOS transistors to their channel regions have become weak; and a severe leakage current issue is generated. Fin field-effect transistors (FinFETs) are a type of multiple-gate devices, which are able to solve the leakage current issue. A typical FinFET structure includes a semiconductor substrate, a plurality of fins protruding from the surface of the semiconductor substrate formed on the semiconductor substrate, gate structures covering portions of side and top surfaces of the fins formed over the semiconductor substrate, and source/drain doping regions formed in the fins at two sides of the gate structures.
Although the FinFET structures may be able to solve the leakage current issue, the performance of the FinFET structures formed by the existing methods needs further improvements. The disclosed methods and semiconductor devices are directed to solve one or more problems set forth above and other problems in the art.